docs: def _process_data(self, sd, ase, offsets, data):
          # type: (SyncCopy, blobxfer.models.synccopy.Descriptor,
          #        blobxfer.models.azure.StorageEntity,
          #        blobxfer.models.synccopy.Offsets, bytes) -> None
          """Process downloaded data for upload
          :param SyncCopy self: this
          :param blobxfer.models.synccopy.Descriptor sd: synccopy descriptor
          :param blobxfer.models.azure.StorageEntity ase: storage entity
          :param blobxfer.models.synccopy.Offsets offsets: offsets
          :param bytes data: data to process
          """
          # issue put data
          self._put_data(sd, ase, offsets, data)
          # accounting
          with self._transfer_lock:
              self._synccopy_bytes_sofar += offsets.num_bytes
          # complete offset upload and save resume state
          sd.complete_offset_upload(offsets.chunk_num)